A.應(yīng)用層 B.網(wǎng)絡(luò)層 C.物理層 D.數(shù)據(jù)鏈路層
A.PPP B.DHCP C.TCP D.UDP
A.126.111.2.3 B.227.100.10.11 C.185.129.22.90 D.221.90.77.23